More particularly, the invention relates to an applicator device for a cosmetic product, comprising:
a body suitable for being held in the hand;
an applicator head;
a wand connecting the body and the applicator head;
the applicator head comprising:
a main body defining a longitudinal axis and comprising a storage portion suitable for loading with product and an application portion suitable for applying the product, passages being provided between said storage portion and said application portion, the storage portion comprising a groove having a main portion defining an axis of extension, the main body of the head having a certain length along the longitudinal axis and the straight portion of the groove extending for a major portion of said length of the main body;
a heating device suitable for heating the cosmetic product loaded on the applicator head, the heating device comprising a heating element lying within said groove.
Document EP1827160A1 discloses an example of such an applicator device, where the heating element is in the form of a twisted or coiled resistance wire helically wound along its extension direction within the groove formed in the applicator head, around a support member of dielectric material. This applicator device has the disadvantage of requiring considerable energy to heat the resistance wire because of its great length, which implies the use of a high power energy source to heat the wire to the desired temperature in order to melt the cosmetic product loaded on the applicator head. When this power source is integrated into the product packaging and application system, and more particularly into the applicator device, it is necessary to provide a housing of sufficient size to accommodate this source of energy, which places significant constraints on the applicator device in terms of size and design.
Moreover, the use of a twisted resistance wire as the heating element in the applicator head also has the disadvantage of requiring a relatively long heating time, about 30 seconds for a head having a length of about 15 to 20 mm for example, until it reaches a temperature sufficient to melt the cosmetic product loaded on the applicator head, making it tedious to use an applicator device equipped with such an applicator head.
In addition, as a twisted resistance wire occupies a significant volume, its integration within the applicator head generates significant conceptual and design constraints.
Finally, the applicator head described in this document EP1827160A1 is highly complex and is inspired by the heating heads of eyelash curlers, which are well known for curling the eyelashes solely with heat, particularly in Asia. These heads are not suitable for both heating and applying a cosmetic product to the eyelashes. As mentioned above, in this type of applicator head, the twisted resistance element is usually placed in a central groove of significant width, which imposes stringent constraints, particularly in terms of applicator head design.
This type of heating head has many other disadvantages, as it can only heat the product on one side of the applicator head and the liquid product once heated is very poorly distributed and therefore very poorly spread out over the head. As a result, the liquid product is not fully applied and accumulates on and around the resistance element.
In addition, the combing means, typically teeth that form a brush, are not very effective because they have to be located on a given area of the head and have no direct fluid communication with the central groove.
Finally, in this type of applicator head, it is not easy to supply cosmetic product to the groove where the resistance element is located, because it is necessary to have a second dedicated device.